Docker network

Presentation By:
Mohammadreza Amini
Amir Arsalan
Spring 2016
IRAN OpenStack Users Group
Docker Networks

Agenda
Docker Networks
| Iran Community OpenStack.ir
The basics of Docker networking
Default Networks
Three Networks
Bridge
None
Host
The default bridge network in detail

Docker Networks

The basic network primitive in Docker is an Ethernet bridge called "docker0."
When Docker boots up on a Linux server, it creates a default docker0 bridge
inside the Linux kernel, and docker0 creates a virtual subnet on the Docker
host. It can pass packets back and forth between containers on that host.
Docker Networks

Docker Networks
Default Networks

Default Network
When you install Docker, it creates three networks automatically. You can list
these networks using the docker network ls command:
$ docker network ls
NETWORK ID NAME DRIVER
7fca4eb8c647 bridge bridge
9f904ee27bf5 none null
cf03ee007fb4 host host
Docker Networks

Three networks
Docker Networks
Historically, these three networks are part of Docker’s implementation.
When you run a container you can use the --net flag to specify which
network you want to run a container on. These three networks are still
available to you.
●
Bridge
●
None
●
Host

Docker Networks
Bridge

Bridge
Docker Networks
The bridge network represents the docker0 network present in all Docker
installations. Unless you specify otherwise with the docker run
--net=<NETWORK> option, the Docker daemon connects containers to this
network by default.

Bridge
Docker Networks
You can see this bridge as part of a host’s network stack by using the
ifconfig command on the host.
$ ifconfig
docker0 Link encap:Ethernet HWaddr 02:42:47:bc:3a:eb
inet addr:172.17.0.1 Bcast:0.0.0.0 Mask:255.255.0.0
inet6 addr: fe80::42:47ff:febc:3aeb/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:9001 Metric:1
RX packets:17 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1100 (1.1 KB) TX bytes:648 (648.0 B)

Docker Networks
None

None
The none network adds a container to a container-specific network stack. That
container lacks a network interface. Attaching to such a container and looking
at it’s stack you see this:
$ docker attach nonenetcontainer
root@0cb243cd1293:/# cat /etc/hosts
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
Docker Networks

Docker Networks
root@0cb243cd1293:/# ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
root@0cb243cd1293:/#

Docker Networks
Host

Docker Networks
Host
The host network adds a container on the hosts network stack. You’ll
find the network configuration inside the container is identical to the
host.

Docker Networks

Docker Networks
The default bridge network is present on all Docker hosts. The docker
network inspect command returns information about a network:

Docker Networks
$ docker network inspect bridge
[
{
"Name": "bridge",
"Id": "f7ab26d71dbd6f557852c7156ae0574bbf62c42f539b50c8ebde0f728a253b6f",
"Scope": "local",
"Driver": "bridge",
"IPAM": {
"Driver": "default",
"Config": [
{
"Subnet": "172.17.0.1/16",
"Gateway": "172.17.0.1"
}
]
},
"Containers": {},
"Options": {
"com.docker.network.bridge.default_bridge": "true",
"com.docker.network.bridge.enable_icc": "true",
"com.docker.network.bridge.enable_ip_masquerade": "true",
"com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
"com.docker.network.bridge.name": "docker0",
"com.docker.network.driver.mtu": "9001"
}

Docker Networks
The Engine automatically creates a Subnet and Gateway to the network. The
docker run command automatically adds new containers to this network.
$ docker run -itd --name=container1 busybox
3386a527aa08b37ea9232cbcace2d2458d49f44bb05a6b775fba7ddd40d8f9
2c
$ docker run -itd --name=container2 busybox
94447ca479852d29aeddca75c28f7104df3c3196d7b6d83061879e33994680
5c

Docker Networks
Inspecting the bridge network again after starting two containers shows
both newly launched containers in the network. Their ids show up in the
container

Docker Networks
$ docker network inspect bridge
{[
{
"Name": "bridge",
"Id":
"f7ab26d71dbd6f557852c7156ae0574bbf62c42f539b50c8ebde0f728a253b6f",
"Scope": "local",
"Driver": "bridge",
"IPAM": {
"Driver": "default",
"Config": [
{
"Subnet": "172.17.0.1/16",
"Gateway": "172.17.0.1"
}
]
},

Docker Networks
"Containers": {
"3386a527aa08b37ea9232cbcace2d2458d49f44bb05a6b775fba7ddd40d8f92c": {
"EndpointID":
"647c12443e91faf0fd508b6edfe59c30b642abb60dfab890b4bdccee38750bc1",
"MacAddress": "02:42:ac:11:00:02",
"IPv4Address": "172.17.0.2/16",
"IPv6Address": ""
},
"94447ca479852d29aeddca75c28f7104df3c3196d7b6d83061879e339946805c": {
"EndpointID":
"b047d090f446ac49747d3c37d63e4307be745876db7f0ceef7b311cbba615f48",
"MacAddress": "02:42:ac:11:00:03",
"IPv4Address": "172.17.0.3/16",
"IPv6Address": ""
}
}

Docker Networks
The docker network inspect command above shows all the connected
containers and their network resources on a given network. Containers in
this default network are able to communicate with each other using IP
addresses

Docker Networks
Any Question?

Docker Network
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Docker Networks
Mohammadreza Amini
Linux/Docker Administrator
Mohammadreza@openstack.ir
Amir Arsalan
Python Developer
Arsalan@openstack.ir
Thank You

Docker network

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